Ultraprocessed Foods Linked to Higher Risk of Knee Arthritis, New Study Finds

Your morning bacon and packaged snacks might be contributing to more than just your waistline—they could be damaging your knees, according to new research.

A groundbreaking study from the University of California, San Francisco (UCSF) has established a connection between ultraprocessed foods and an increased risk of knee osteoarthritis, regardless of a person’s weight or exercise habits.

“Over the past decades, in parallel to the rising prevalences of obesity and knee osteoarthritis, the use of natural ingredients in our diets has steadily diminished,” explained Dr. Zehra Akkaya, the study’s lead author and UCSF researcher.

Ultraprocessed foods—designed for extended shelf life, strong flavor appeal and convenience—include common items like breakfast cereals, bacon, hot dogs, pre-packaged snacks and sweets. These foods now constitute a significant portion of many Americans’ diets, with study participants consuming approximately 41% of their daily calories from ultraprocessed sources.

The research team analyzed data from the Osteoarthritis Initiative, a comprehensive public research project focused on knee conditions. They examined 615 individuals who had not yet developed osteoarthritis, using non-enhanced MRI scans to detect fat infiltration in thigh muscles—a key indicator of potential knee problems.

Results published in the journal Radiology revealed a clear correlation: the more ultraprocessed foods people consumed, the higher the amount of fat stored within their thigh muscles. This held true regardless of total calorie intake, body weight or exercise frequency.

“When fat gets into the muscle, it weakens the support system for the knee, leading to more joint stress and inflammation,” Dr. Akkaya noted. This muscle deterioration, characterized by streaks of fat replacing healthy muscle fibers in the thigh, creates a perfect storm for joint degeneration.

The findings are particularly significant given the massive economic burden of knee osteoarthritis, which Dr. Akkaya describes as “one of the largest non-cancer-related healthcare costs in the United States and around the world.”

Previous research into knee osteoarthritis—commonly known as a “wear-and-tear” condition—had established that higher amounts of intramuscular fat in the thigh could increase the risk of developing the condition. What makes this new study notable is the direct link to dietary choices, specifically ultraprocessed foods.

Even individuals who appear outwardly healthy could be at risk. The study found that even “thin” or physically active people who consumed significant amounts of ultraprocessed foods showed signs of compromised muscle quality, potentially leading to knee issues later in life.

While the research team acknowledges certain limitations—the study showed correlation rather than definitive causation, and relied on self-reported dietary information—the implications are clear. Reducing ultraprocessed food consumption may help preserve muscle quality and potentially alleviate the burden of knee osteoarthritis.

This research arrives amid growing concern about ultraprocessed foods, which have previously been linked to other health issues including obesity, cardiovascular disease, and certain cancers. The UCSF study adds joint health to the list of concerns, providing yet another reason to reconsider dietary choices.

For consumers looking to protect their joint health, experts recommend adopting a balanced diet rich in whole foods and maintaining regular physical activity. Particular attention should be paid to reducing consumption of highly processed meat products like bacon, which the study specifically highlighted as problematic.

As research continues to reveal the far-reaching impacts of our modern food system, this study offers compelling evidence that what we eat affects not just our overall health, but also the specific mechanisms that keep our joints functioning properly throughout life.